The second of two storms will bring an end to the brief respite from the cold of December. One system brought significant precipitation to the western Wyoming mountains and valleys early Thursday. Due to the unseasonably warm air accompanying the system, Star Valley experienced more rain than snow with little accumulation on the valley floor. While total precipitation, as measured by the weather stations in the valley, ranged upwards of half an inch, only a inch or two of wet snow was observed. This was not the case in higher elevations above about 7000 feet with around a foot observed in parts of the Wyoming Range and from 1-2 feet in the Tetons. The following chart was produced by Riverton WFO showing the observed snowfall from the first storm.
Very strong winds were observed across the high country, with Mt Coffin in the Wyoming range reporting gusts to 134 mph Thursday morning.
Warm air continued to cover the area through Friday with afternoon temperatures into the mid 40s under quite a bit of late December sunshine.
Storm number 2 now moving through the Pacific Northwest will bring an end to the brief respite from winter cold. Rain and snow will spread across Star Valley, beginning later Friday evening, becoming all snow after midnight. The cold front will arrive prior to sunrise accompanied by strong, gusty winds and 2-3 hours of moderate to heavy snow. The snow should decrease to showers/flurries by later Saturday morning, however. cold air will drop temperatures to well below freezing during the afternoon. Given the rapid movement of the storms, snow totals should generally range from 3-6 inches with the greatest potential in the northern portion of the valley.
High pressure then builds into the area by New Years Day and will dominate into the middle of the first week of the New Year. This returns Star Valley to weather experienced much of December, cold nights with sunshine most days. Overnight temperatures will drop below zero in colder valley locations, then struggle to reach the teens during the afternoon, given the low sun angle this time or year.
The next chance of significant snow should not occur until after midweek.